x(y-3)-(2y-6) =x(y-3)-2(y-3)=(y-3)(x-2) (x+y)^3-(x-y)^2(x+y) =(x+y)[(x+y)²-(x-y)²]=4xy(x+y) x(x^2-xy)-(4x^2-4xy)=x²(x-y)-4x(x-y)=x(x-y)(x-4)